The present invention is concerned with ferrous sulphate heptahydrate, and, more particularly, making ferrous sulphate in granular form.
Ferrous sulphate heptahydrate has the chemical formula FeSO.sub.4. 7H.sub.2 O and may be alternatively referred to as copperas, being green in colour. It is a by-product which is produced primarily in the manufacture of titanium dioxide and, with pH-values of between 1 and 2, it is a highly acid salt. It may be used inter alia as a flocculating agent in cleaning waste water, and as a catalyst in the hydrogenating liquefaction of coal.
However, handling ferrous sulphate heptahydrate often gives rise to fairly serious difficulties, firstly because of its very acid nature and secondly because of the high residual content of moisture clinging thereto. Because of the former consideration for example it must be stored in suitably acid-resistant containers. In regard to the second consideration, if the substance is to be put into storage, the high residual moisture content thereof usually makes it necessary to take particular steps to ensure that the ferrous sulphate heptahydrate does not stick together to form lumps, for such lumps would tend severely to limit the pourability thereof, to such an extent that it may be possible to remove it from the container only by means of extensive loosening operations to break up the lumps again. In addition, storage containers require expensive cladding in order to protect the walls of the containers and other elements from corrosion.